~ chicken-core (master) 801328605663461a43e9f5b1d6e2269c127f42cc

commit 801328605663461a43e9f5b1d6e2269c127f42cc
Author:     felix <felix@call-with-current-continuation.org>
AuthorDate: Tue Jul 7 22:20:54 2026 +0200
Commit:     felix <felix@call-with-current-continuation.org>
CommitDate: Tue Jul 7 22:20:54 2026 +0200

    catch any exceptions when executing process in forked thunk to avoid process hanging in limbo
    
    When starting a process using the "process[*]" primitive, the particular
    combination of process-fork (with a thunk) and an executable name with
    an argument list, where execvp(2) fails could result in the forked process
    being in some "limbo" state, that is, not terminated and still alive.
    
    A waitpid(2) on the forked process will wait indefinitely, as the process
    never dies. The reason is not clear to me, but I assume this is related
    to the context set up by certain eldritch arcana we perform to minimize
    life data. The problem can be reproduced by invoking
    
      (process "/does/not/exist" '())
    
    The problem also exist in C5.
    
    This problem was reported by Stanislav Kljuhhin.

diff --git a/posixunix.scm b/posixunix.scm
index a9f0ebd6..3b6ee2b4 100644
--- a/posixunix.scm
+++ b/posixunix.scm
@@ -1114,7 +1114,8 @@ static int set_file_mtime(C_word filename, C_word atime, C_word mtime)
               ((fx= 0 pid)              ; child process
                (set! children '())
                (when killothers
-                 (call-with-current-continuation (lambda (continue) (##sys#kill-other-threads (lambda () (continue #f))))))
+                 (call-with-current-continuation 
+                   (lambda (continue) (##sys#kill-other-threads (lambda () (continue #f))))))
                (if thunk
                    (##sys#call-with-cthulhu
                     (lambda ()
@@ -1251,7 +1252,11 @@ static int set_file_mtime(C_word filename, C_word atime, C_word mtime)
 		     (connect-child loc opipe stdinf chicken.file.posix#fileno/stdin)
 		     (connect-child loc (swapped-ends ipipe) stdoutf chicken.file.posix#fileno/stdout)
 		     (connect-child loc (swapped-ends epipe) stderrf chicken.file.posix#fileno/stderr)
-		     (chicken.process#process-execute cmd args env)))) ) ) ))
+		     (handle-exceptions ex
+                        (begin
+                          (print-error-message ex ##sys#standard-error)
+                          (##core#inline "C_exit_runtime" 126))
+                        (chicken.process#process-execute cmd args env)))) ) ) )))
           [input-port
             (lambda (loc cmd pipe stdf stdfd on-close enc)
               (and-let* ([fd (connect-parent loc pipe stdf stdfd)])